The functions of the steering column switch can be subdivided into two main blocks:
Furthermore, the signals are forwarded to the priming caps to activate the driver's airbag stages 1 and 2 by the steering column switch.
The multifunction steering wheel provides the means by which the driver can easily and ergonomically perform the following functions:
The multifunction steering wheel consists of:
Located below the multifunction steering wheel are
The signal transfer from the steering wheel to the steering column electronics (control unit for steering column switch) is ensured by a coil spring conductor.
The turn indicator-low beam switch consists of
The turn signal/dip switch also incorporates two axial touch switches.
Transfer concept: steering column stalks and axial touch buttons have differing signal transmission routes:
Steering column stalk signal transmission route: When the driver operates the steering column lever, a message is sent to the light module.
Signal path: steering column switch -> data bus CAN -> Body Gateway Module -> data bus K-CAN -> light module.
For safety reasons, there is an additional serial cable from the steering column switch to the light module. An analogue coded signal is applied to that cable and is analysed by the light module. Each switch position is allocated a voltage range. The serial cable enables transmission of all positions of the turn signal/dip switch in the event of a bus fault, though with some limitations to the possible functions:
Touch button signal transmission path: When the driver operates one of the axial touch buttons, a message is sent to the instrument cluster.
Signal path: steering column switch -> data bus CAN -> Body Gateway Module -> data bus K-CAN -> instrument cluster.
The lever for the cruise-control system consists of
Transfer concept: When the driver operates the steering-column lever or the axial one-touch button, a message is sent to the digital engine electronics.
Signal path: steering column switch -> data bus PT CAN -> Digital Engine Electronics.
Transfer concept: When the driver operates the knurled wheel, a message is sent to the Active Cruise Control (ACC) control unit.
Signal path: steering column switch -> data bus PT CAN -> active cruise control (ACC).
The wiper switch consists of:
Transfer concept: When the driver operates the steering column lever, a message is sent to the body base module.
When the driver operates the axial button or the adjuster wheel,
Signal path: steering column switch -> data bus PT CAN -> Body Gateway Module -> data bus K-CAN -> body base module and/or rain/driving light sensor.
The function buttons enable selection of
The steering wheel position is adjusted electrically by means of a switch. The switch has four possible directions of movement. These enable the steering wheel to be moved up, down, forwards or backwards.
Transfer concept: When the driver operates the switch for steering column adjustment, a message is sent to the centre console switching centre.
Signal path: steering column switch -> data bus PT CAN -> Body-Gateway Module -> data bus K-CAN -> centre console switching centre
The fanfare horns serve both as a warning signal and as redundant-system audible alarms of the vehicle.
The directly read horn switch signal is sent as a valid status via the steering wheel module and the coil spring conductor to the steering column switch SZL. The steering column switching centre can control the high-tone and low-tone horns separately.
The steering wheel heating system consists of
The steering column switch activates the heater mat as required in order to ensure even heating of the steering wheel.